Problem: Which of these numbers is composite? ${19,\ 23,\ 35,\ 37,\ 41}$
Solution: A composite number is a number that has more than two factors (including 1 and itself). 19, 23, 37, and 41 each have only two factors. The factors of 35 are 1, 5, 7, and 35. Thus, 35 is the composite number.